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Just received Mutec MC-3+ USB this afternoon. I have it set up to go thru AES connection. First impression is very positive. Improvement over stock Yggy and the low cost "Breeze". What has surprised me is that the sq seems more liquid/smoother while retaining the Yggy's detail. Will fool around some more and will give further impressions early next week.

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There are many USB "treatments" on the market to either re-clock, filter, regenerate, or provide isolation. It is difficult to find the right mix, with some units requiring a power supply, which adds another dimension in angst as to find a a low power linear supply which won't affect either AC or DC outputs. Others can react with the cables adversely, we do live in exciting times.

Being familiar with the sound performance of the Mutec MC-1.2, the attraction of a galvanic isolation DDC in the Mutec MC-3+USB was a very tempting upgrade. When it worked, the Intona 7054 worked well with the MC-1.2 and was hoping the MC-3+USB would be at least equal.

I need to be careful here, since I haven't experienced DSD256 native. I didn't want to download new DSD256 music, since I am not familiar with it.

HQ Player can upsample anything to DSD256 and the MC-3+USB can accept it, but I am unsure of the benefits and will keep an open mind. First impressions are the sound became thin and lacking in body and dynamics, notably in the bass. The sound stage narrows sharply and focus of individual instruments is a problem. Micro details are there, but should be more pronounced. After a time the sound is uncomfortable and difficult to listen to, on widely different tracks, a symptom is that things are not right.

AC/DC [sHM-CD] "Let there be Rock" opening sounds a true cacophony upsampled to DSD256, whereas there are only four instruments which are readily decipherable. There's obvious distortion of the guitars but the drums should be prominent and accurate. Shelby Lynne's "Just a little Lovin" is lost at sea, nothing much of the soundstage at all, the minutest of details are gone including reverb and tape hiss. Oh dear, what's going on, is the problem the player or the DDC? Sophie Milman's "So Sorry" lacks any emotion, I usually hear the vocals very prominent across the stage, and when an accent is sung, it's nicely defined and you can every inflection, usually.

I was ready to throw in the towel and Mr. Mutec kindly offered me a refund. Dang, there has to be a reason why the sound was so bad. One always learns from errors, and making a discovery is a bonus. Out came the multimeter, not really all that keen to rip open expensive USB cables, but the USB shells are easy to get to, let's see. A common reference point was used in the power distributor spare receptacle's earth pin to each of the shells.

HQ Player was still output DSD256 into the MC-3+USB and all measurements are in a live system. The Lenovo m93P tiny's shell to earth measured 85mV AC. OK, that's where the sound is crap and this is the same voltage that appears at the MC-3+USB USB input. I shorted the earth connection to the shell, no major change to the sound, so that method doesn't work.

Substituted the Lenovo for MacbookPro running on batteries, same HQPlayer output DSD256, same tracks. The measured voltage now was 240mV AC. The sound... IMPROVED to jaw dropping :)Soundstage back to normal wide levels, far, far less distortion, especially in the treble, blacker blacks. Wow. Here's the mother load. Soundstage and dynamics are back in abundance, sibilance is under control, and AC/DC's "Dirty Deeds done dirt cheap" dynamics actually tempts you with evil thoughts of the back door man. When a comparison is made to the spinning CD of Sophie Milman's "In the Moonlight" and the Mutec/HQPlayer the CD still has the edge in finer detail, and that accuracy of vocal reproduction with excellent micro details. Moving on...

The isolation transformer used for the Lenovo's laptop type power supply was removed, to let the balanced AC supply do its work. From 85mV previously on the shell to earth, the voltage was now 260mV. Sound was still great, why not add in the Intona 7054 & see what happens, it's kinda lonely by itself. The voltage at the MC-3+USB increased to 360mV (further above earth = better sound quality) and that slight edginess had gone from the vocals, overall, not a large change but noticeable and enough to keep in place.

Mr. Mutec is not going to be receiving the MC-3+USB back unless it fails for some reason, it's definitely a stayer.

For the computer, Task Manager logged 20% CPU duty for HQ Player 3.13.0 up sampling to DSD256. There was no stutter at any time. For PCM up sampling to 192kHz, the CPU logs 0.7%.

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I wonder how the USB/SPDIF converter in the Mutek sounds in comparison to the Berkeley Alpha USB, which also does galvanic isolation. The Alpha was released about five years ago, has newer and cheaper technology surpassed it yet?

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I wonder how the USB/SPDIF converter in the Mutek sounds in comparison to the Berkeley Alpha USB, which also does galvanic isolation. The Alpha was released about five years ago, has newer and cheaper technology surpassed it yet?

Yeah has it ?

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I wonder how the USB/SPDIF converter in the Mutek sounds in comparison to the Berkeley Alpha USB, which also does galvanic isolation. The Alpha was released about five years ago, has newer and cheaper technology surpassed it yet?

Does anyone know how much the galvanic isolation modules in the Berkeley Alpha USB is? Not that my search skills are perfect, but there's no mention of what the level is. What about the clock rate? Both values for the MC-3+USB are stated.

The MC-3+USB can reclock the output, or receive an external clock, and can be adjusted to suit the output device, the BAD Alpha USB cannot. DSD is a big issue, the Alpha cannot accept DSD64 let alone DSD256. DSD to PCM conversion is very good in the Mutec, am surprised how good. Five years in a long time in computer audio. So just on paper already there's flexibility built in and speaking of paper the MC-3+USB is cheaper than the Alpha USB, and ROHS.

I feel like delivering a sales pitch, I don't work for Mutec, just a very satisfied user.

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I tried to converse on the German forum, which was not that easy for me given my lack of mastering the German language ; Google Translate is your friend to a certain but limited extent :-). I am anyhow happy to share a few information I gathered there, especially from Fujak, the person who tested Mutec MC-3+ cascades.

- on the possibility to use an external 10 MHz clock ; Fujak has built his own external clock and stated that he was not able to witness any improvement with this DIY clock fed into the MC-3+ USB, compared to a cascade of 2 x MC-3+ USB devices. Fujak did not report being able to test a prototype of the Ref10 from Mutec anyhow. We will see what that brings when this new product will be available.

- on the cascading of 2 x MC-3+ USB devices ; Fujak strongly recommends to use BNC connections between the devices and to the DAC (better quality for the buck of BNC cables than AES ones). He uses Oyaide DB-510 cables to do that. Kujak made the precision that the two MC-3+ USB need to be configured with internal clock reclocking (using the clock signal from the first to synchronize the second does not help reach better SQ).

- on the upsampling question I was raising (24/192 before reclocking instead of 16/44 to the reclocker and upsampling at the DAC) : there are other reports by the German forum users that upsampling to 24/192 before a 24/192 DAC brings better SQ. There is an ongoing thread on this subject.

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So you have witnessed that the Intona was bringing additional quality (360mV vs 260mV) to the signal on the input of the Mutec is it correct ?

Is the improvement audible in your opinion ?

The voltages were measured with a Fluke 114, so it doesn't include "much" lower order RF. Today, I moved the Mutec and the Intona about retaining the same cabling and the voltages dropped to about 85 mV again, so thought uh oh, but everything played well, so go figure Maria.

For fun I added an 'old' original ifi USB and this lifted the volts about 100mV on the original setup, but for SQ it didn't do much. The idea was to lift the shells further above earth which it did. It was mainly to aid in the transmission properties, but that process added another two USB cables, I prefer to keep these at minimum.

The Intona was a worthwhile inclusion, it had less effect than compared with the MC-1.2 which was a dramatic change. The extra isolation, just polished the final shine, if you use Meguiars Final Inspection for cars, there's the analogy. As always, the choice of cabling is important, just might try the Curious Cables again, now that I know what to look for, even though maybe rough road to get there.

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The voltages were measured with a Fluke 114, so it doesn't include "much" lower order RF. Today, I moved the Mutec and the Intona about retaining the same cabling and the voltages dropped to about 85 mV again, so thought uh oh, but everything played well, so go figure Maria. [...]

If I read correctly, you seem to be using the voltage between the USB shell and AC ground to predict how good things would sound. And the higher the voltage, the better things would sound. Is that correct? What's the reason behind that?

People who do AC polarity measurements normally choose the polarity that shows lower component ground to AC ground voltage. But that's done component by component, not in a live system with everything hooked up. Off the top of the head, I don't have anything in my system that is more than 50mv vs AC ground when measured in isolation...

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If I read correctly, you seem to be using the voltage between the USB shell and AC ground to predict how good things would sound. And the higher the voltage, the better things would sound. Is that correct? What's the reason behind that?

People who do AC polarity measurements normally choose the polarity that shows lower component ground to AC ground voltage. But that's done component by component, not in a live system with everything hooked up. Off the top of the head, I don't have anything in my system that is more than 50mv vs AC ground when measured in isolation...

Well, the lower the better is considered ideal, now measuring at different times of the day, the voltage increases from the shell to earth as the night goes on....which leads down another path of mystery. The frame of a workstation desktop and the Equitech transformer frame are tied to each other by a 6mm cable (all I had kicking about), the voltage difference between the two is 18 mV and also to the shell at the desktop is at earth potential, whereas the Lenovo tiny floats above earth.

The higher the voltage above ground certainly did improve the sound, or rather removed the added crud. Where shield currents rear their ugly head, the whole of the system needs a looking at, then pinpointing the problem to one component.

Probably the main issue here is the isolation transformer that was fitted to the Lenovo PC's switchmode power supply was removed, allowing the same AC voltage references to occur over the PC and the Mutec. Perhaps the USB shields were carrying too much (crud) content from the PC to the Mutec and could not reference back to the main AC supply. The Mutec outputs are certainly grounded, so it's one way street. Makes me think twice about isolation transformers for individual components.

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Just received Mutec MC-3+ USB this afternoon. I have it set up to go thru AES connection. First impression is very positive. Improvement over stock Yggy and the low cost "Breeze". What has surprised me is that the sq seems more liquid/smoother while retaining the Yggy's detail. Will fool around some more and will give further impressions early next week.

If you don't mind me asking, what interface are you using in your server to feed the Mutec?

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I'm kind of intellectually reticent to stacking those filters, use more curious cables, aso...

I'm using two MC-3+ USB stacked in the way Fujak documented. I'm very happy with that for the moment :-)

For stacking two Intonas on second thought, there will be a problem if the DAC front end can draw too much current. The Intona can drop from 500mA to 300mA at peak, so the second Intona is behind the eight ball already and can't supply enough current for the DAC. The power for the 2nd Intona will be gobbled up by itself, leaving only drips to be used by the DAC. No, not all that great.

On the topic of stacking MC-3+USB. Is the way I look at this correct:

If the signal is PCM, there's no harm for a player like Audirvana + or HQ Player to upsample to the maximum of 192 kHz. Let the DAC have an easier filtering time. The same 192 kHz signal needs to be the same from Digital to Digital Conveter (DDC) 1 to DDC 2. The MC-3+USB is good, but it's not an SRC Master It's a Clock Master. From DDC 2 the output is 192 kHz PCM. If the sampling frequency is the same, then the gear changing time would be minimal, otherwise there's 3 time lags, the two DDC plus the DAC.

For DSD it's similar, however the maximum sampling frequency output is 176.4 kHz, and that should pass through to the DAC as such.

On the topic of Fujak's cabling. Yes the cable price an hurt, AES3 just by technique can drown noise (since ~ 1932). I had two quality instances for different Oyaide cables as a passing comment. Plus the long lead time and a woeful US distributor has sadly put Oyaide on my black list. DH Labs, Blue Jeans, Wireworld, Monoprice at the other end + quite a few others can make good quality AES3 cables.

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Thanks - did you mean the motherboard USB or are you using a PCIe USB card of some type?

Motherboard (Asus Sabertooth) USB from my Puget Sound Serenity Pro . I also have a CAPS pipeline with SOTM USB Card but have not tried that combo yet. Will also try Mutec with some of the USB gadgets (Regen and Wyred Recovery) when I have some more time.

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The Mutec MC-3+USB isn't that fond of USB 3.0 ports, with or without the Intona. The blue lock light was on, but no signal coming through. If there's a self powered USB 2.0 hub on the USB 3.0 port, the Mutec is OK, but the hub is a nuisance connection. Even more if the hub is powered from a wall wart.

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The Mutec MC-3+USB isn't that fond of USB 3.0 ports, with or without the Intona. The blue lock light was on, but no signal coming through. If there's a self powered USB 2.0 hub on the USB 3.0 port, the Mutec is OK, but the hub is a nuisance connection. Even more if the hub is powered from a wall wart.

USB 2.0 ports work with not a problem, first time every time.

Hmm. I don't have Intona but am using USB 3.0 port from PC without any issue (so far).

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Motherboard (Asus Sabertooth) USB from my Puget Sound Serenity Pro . I also have a CAPS pipeline with SOTM USB Card but have not tried that combo yet. Will also try Mutec with some of the USB gadgets (Regen and Wyred Recovery) when I have some more time.

Very interesting... The CAPS/SOTM vs the Serenity Pro would indeed be a neat comparison with the Mutec.

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Very interesting... The CAPS/SOTM vs the Serenity Pro would indeed be a neat comparison with the Mutec.

Main reason I am using Serenity Pro more these days is that I am using Roon almost exclusively and the Serenity has Roon Core installed on it. I have Roon Server installed on CAPS but find it's more buggy. My understanding is that the next Roon update will have Roon endpoints. Hopefully this will make it easier to to send audio signal to the CAPS machine.